Infusion pump system, an infusion pump unit and an infusion pump

ABSTRACT

An infusion pump unit includes a housing sized to allow the pump unit to be carried as a portable unit. The housing contains a controllable pumping system for pumping fluid. The pump actuator is lighter, smaller, quieter and less power consuming.

The present invention generally relates to the technical field ofinfusing a liquid to a patient or person by means of an infusion pump,e.g. at a hospital. The present invention also relates to infusion ofliquid to an animal. More precisely, the present invention relates to aninfusion pump system and an infusion pump unit of a universal applicablestructure for infusing a liquid into a patient or person.

At hospitals or nurse houses, it is often necessary to supply medicationor body liquids to a person by means of an infusion pump in whichinstance the medication or the body liquids are infused into the body ofthe patient or person in question through a catheter which is connectedto the blood transportation system of the patient or person, e.g. a veinor a venule. The usual technique of supplying medication by means of aninfusion system to a patient or person involves the supply ofphysiologic liquid to the patient which physiologic volume is suppliedat a specific rate and which serves as a diluting liquid as themedication is supplied to the physiologic liquid also at a specific ratesuch as one or two drops of medication per time period varying from asecond or a few seconds to several minutes or even hours. The medicationof a patient or person may in some applications involve the supply ofthe medication directly to the patient or person by means of theinfusion pump.

U.S. Pat. No. 6,270,478 discloses an infusion pump system allowing thepatient or person using the infusion pump system to shift from aposition sitting or lying in a bed and move around without necessitatingthe substitution or shift of the stationary infusion pump to a portableinfusion pump as the infusion pump system constitutes a universallyapplicable or combined portable and stationary infusion pump system.

An advantage of this known system relates to the fact that the infusionpump system may be used in different pumping modes as the infusion pumpsystem includes several programmes for different operational modes andfurther preferably includes input means for input of differentoperational programmes. U.S. Pat. No. 6,270,478 is hereby incorporatedherein by reference.

The pump actuator of the infusion pump units of this known systemcomprises a magnetic core and a solenoid coil. This actuator is ratherbulky, noisy and heavy and requires a relatively large input ofelectrical energy.

It is an object of the present invention to provide an infusion pumpsystem, an infusion pump unit for said system and an infusion pump ingeneral were the pump actuator is lighter, smaller, quieter and lesspower consuming.

According to one aspect of the invention this object is achieved byproviding a shape memory alloy actuator as the pump actuator, and saidshape memory actuator comprises:

-   -   a body arranged displaceable between a first and a second        position,    -   releasable holding means adapted for holding said body in said        first position,    -   at least one first and at least one second wire made of a shape        memory alloy such as nitinol, said first wire being at one end        connected to said body such that shortening of the length of        said first wire exerts a force on said body for moving said body        from said second to said first position, and    -   a biasing means, such as a tension spring, a compression spring,        a straight or arcuate flat spring or a piston and cylinder        mechanism, arranged and adapted for biasing said body for moving        said body from said first to said second position,    -   said second wire having one end connected to said holding means        such that shortening of the length of said second wire releases        said holding means for allowing said biasing means to move said        body from said first position to said second position.

According to another aspect this object is obtained by providing a shapememory alloy actuator as the pump actuator, and said shape memoryactuator comprises:

-   -   a body arranged displaceable between a first and a second        position,    -   at least one first wire made of a shape memory alloy such as        nitinol, said first wire being at one end connected to said body        such that shortening of the length of said first wire exerts a        force on said body for moving said body from said second to said        first position,    -   a biasing means, such as a tension spring, a compression spring,        a straight or arcuate flat spring or a piston and cylinder        mechanism, and    -   a rotatably arranged intermediate member such as a lever or a        disc connected to said body and to said biasing means,

said biasing means being adapted for exerting a rotation force on saidintermediate member for rotating said intermediate member around an axisof rotation in a first direction of rotation from a first angularposition to a second angular position, said intermediate member beingconnected to said body such that rotation of said intermediate member insaid first direction of rotation displaces said body from said firstposition to said second position, and

said biasing means and said intermediate member being arranged andadapted such that the lever or moment arm of said rotation force withrespect to said axis of rotation is larger when said intermediate memberis in said second angular position than when said intermediate member isin said first angular position such that said lever or moment arm ofsaid rotation force increases when said intermediate member rotates insaid first direction of rotation.

According to a yet further aspect of the invention this object isachieved by providing a shape memory alloy actuator as the pumpactuator, and said shape memory actuator comprises:

-   -   a body arranged displaceable between a first and a second        position,    -   at least one first wire made of a shape memory alloy such as        nitinol, said first wire being at one end connected to said body        such that shortening of the length of said first wire exerts a        force on said body for moving said body from said second to said        first position,    -   a biasing means, such as a tension spring, a compression spring,        a straight or arcuate flat spring or a piston and cylinder        mechanism, and    -   a rotatably arranged intermediate member such as a lever or an        arm connected to said body at a force transmission point on said        body and connected to or integral with said biasing means,

said biasing means being adapted for exerting a rotation force on saidintermediate member for rotating said intermediate member around an axisof rotation in a first direction of rotation from a first angularposition to a second angular position, said intermediate member beingconnected to said body such that rotation of said intermediate member insaid first direction of rotation displaces said body in from said firstposition to said second position, and

said intermediate member and said body being arranged and adapted suchthat said rotation force is transmitted to said body as a displacementforce applied at said force transmission point for moving said body fromsaid first to said second position, and such that the lever or momentarm of said displacement force with respect to said axis of rotation islarger when said intermediate member is in said first angular positionthan when said intermediate member is in said second angular positionsuch that said lever or moment arm of said displacement force withrespect to said axis of rotation

Hereby a quiet, light, mechanically efficient and compact infusion pumpis obtained.

In a yet further aspect the present invention relates to a fluid pump,preferably for use in an infusion pump system, an infusion pump unit oras an infusion pump, said fluid pump comprising:

-   -   a flexible tube connected to a fluid inlet at one end and        connected to a fluid exit at the opposite end,    -   at least three flattening bodies for flattening said tube        against an abutment element and arranged along the length of        said tube, said bodies being arranged displaceable between a        first position, wherein said body is pressed against said        abutment element with said tube flattened between said body and        said abutment element, and a second position spaced so far from        said abutment element that said tube at least partly has        regained an open configuration,    -   at least one first wire for each flattening body and made of a        shape memory alloy, said first wire being at one end connected        to said body such that shortening of the length of said first        wire exerts a force on said body for moving said body from said        first to said second position, and    -   a biasing means, such as a tension spring, a compression spring,        a straight or arcuate flat spring or a piston and cylinder        mechanism, for each of said flattening bodies and connected to        said flattening body such that a biasing force is exerted on        said flattening body in a direction from said second position to        said first position.

Hereby an exceptionally light, simple and quiet infusion pump isobtained where the elements that are to be replaced for each infusionare relatively inexpensive and easy to replace.

In a yet further aspect the present invention relates to an infusionpump for infusing a fluid or a paste in a patient, preferably a portableinfusion pump and preferably for use in infusing insulin or a painkiller fluid in a patient, said infusion pump comprising:

-   -   a housing,    -   a cartridge, ampoule or syringe containing said fluid or paste        and removably arranged in said housing and having an outlet        aperture and a piston element slidably arranged inside said        syringe such that said piston is displaceable towards said        outlet aperture,    -   a spindle connected to said piston element and arranged such        that rotation of said spindle in a first rotational direction        displaces said piston towards said outlet aperture    -   a shape memory alloy actuator incorporated in a shape memory        alloy motor comprising:    -   said shape memory alloy actuator having:        -   a body arranged displaceable between a first and a second            position,        -   at least one first wire made of a shape memory alloy such as            nitinol, said first wire being at one end connected to said            body such that shortening of the length of said first wire            exerts a first displacement force on said body for moving            said body from said second to said first position,        -   a biasing means, such as a tension spring, a compression            spring, a straight or arcuate flat spring or a piston and            cylinder mechanism arranged and adapted for exerting a            second displacement force on said body for moving said body            from said first to said second position,    -   and    -   a gear having a first and second rotation direction, said body        having a portion adapted to fit between two adjacent teeth of        said gear, and said body and said gear being adapted and        arranged such that in said first position said portion is        located between a pair of teeth of said gear and in said second        position said portion is located between the adjacent pair of        teeth of said gear reckoned in said second rotation direction of        said gear such that said second displacement force will cause        said body to rotate said gear in said first direction, and

said gear being connected to said spindle, preferably via at least onefurther gear such that rotation of said gear in said first directioncauses said spindle to rotate in said first rotational direction.

In a yet further aspect the present invention relates to an infusionpump for infusing a fluid or a paste in a patient, preferably a portableinfusion pump and preferably for use in infusing insulin or a painkiller fluid in a patient, said infusion pump comprising:

-   -   a housing,    -   a cartridge, ampoule or syringe containing said fluid or paste        and removably arranged in said housing and having an outlet        aperture and a piston element slidably arranged inside said        syringe such that said piston is displaceable towards said        outlet aperture,    -   said shape memory alloy actuator, having        -   a body arranged displaceable between a first and a second            position,        -   at least one first wire made of a shape memory alloy such as            nitinol, said first wire being at one end connected to said            body such that shortening of the length of said first wire            exerts a first displacement force on said body for moving            said body from said second to said first position,        -   a biasing means, such as a tension spring, a compression            spring, a straight or arcuate flat spring or a piston and            cylinder mechanism arranged and adapted for exerting a            second displacement force on said body for moving said body            from said first to said second position,    -   and    -   a rack having a first and second displacement direction and        abutting said piston such that displacement of said rack in said        second displacement direction displaces said piston towards said        outlet aperture,

said body having a portion adapted to fit between two adjacent teeth ofsaid rack, and said body and said rack being adapted and arranged suchthat in said first position said portion is located between a pair ofteeth of said rack and in said second position said portion is locatedbetween the adjacent pair of teeth of said gear reckoned in said seconddisplacement direction of said rack such that said second displacementforce will cause said body to displace said rack in said firstdirection.

In a final aspect the present invention relates to an infusion pumpsystem, comprising:

-   -   at least one infusion pump unit, comprising:    -   a housing of a size allowing said infusion pump unit to be        carried by a user as a portable infusion pump unit, said housing        defining an exterior surface,    -   a fluid inlet provided accessibly at said exterior surface for        establishing fluid communication from an external infusion bag        to said fluid inlet,    -   a fluid outlet provided accessibly at said exterior surface for        establishing fluid communication to an infusion site,    -   a controllable pumping system included within said housing and        having an inlet and an outlet, said inlet being connected to        said fluid inlet and said outlet being connected to said fluid        outlet for allowing transfer of fluid from said fluid inlet to        said fluid outlet through activating said controllable pumping        system,    -   an electronic control means received within said housing for        controlling the operation of said controllable pumping system,        said electronic control means including at least two preset        pumping programs for allowing said controllable pumping system        to be controlled in at least two alternative infusion pumping        operations, and    -   a power supply unit housed within said housing for supplying        power to said controllable pumping system and to said electronic        control means and connectible through exterior terminals        provided at said exterior surface of said housing to external        electric energy supply means,

a stationary receptor system including:

-   -   at least one receptor means for receiving and fixating one of        said infusion pump unit therein so as to maintain said infusion        pump unit in a stationary mode and exposing said fluid inlet and        fluid outlet of said infusion pump unit for allowing access        thereto and having first terminals connectible to said exterior        terminals for supplying said electric energy to said power        supply unit of said at least one infusion pump unit and further        having second terminals connectible to third terminals of a        second receptor means for supplying power to said second        receptor means,    -   a mains supply unit for receiving electric energy from the mains        supply and having second terminals connectible to said third        terminals for supplying said electric energy to said receptor        means and thereby to said power supply unit of said at least one        infusion pump unit, said mains supply unit constituting said        external electric supply means, and    -   fastening means for fastening said receptor means adjacent one        another and for fastening said mains supply unit adjacent one of        said receptor means.

In the currently preferred embodiment, said system further comprises acarrier frame for carrying one infusion pump unit and provided withreceiving means for receiving said infusion pump unit and preferablywith releasable holding means for holding a container of infusion fluidcommunicating with said fluid inlet of said infusion pump unit, saidreceptor means and said carrier frame having cooperating connectionmeans for allowing said frame to be connected to said receptor meanssuch that said external terminals are connected to said first terminals.

Hereby a flexible system is obtained where an optional number ofreceptor means may be arranged adjacent one another and where greatflexibility is achieved as to the transport of an infusion pump unitwith the corresponding patient.

In the following the invention will be explained more in detail inconnection with various embodiments thereof shown, solely by way ofexample, in the accompanying drawings in which

FIG. 1 is a perspective and schematic view of a first embodiment of aportable infusion pump unit according to the present invention,

FIG. 2 is an elevational and partly sectional view of the firstembodiment of the portable infusion pump unit illustrated in FIG. 1,

FIG. 3 is a schematic view of the interior of the first embodiment ofthe portable infusion pump unit illustrated in FIGS. 1 and 2, disclosingthe flow path thereof,

FIG. 4 is a schematic view illustrating a possible application of thefirst embodiment of the portable infusion pump unit illustrated in FIGS.1, 2 and 3,

FIG. 5 is a perspective and schematic view illustrating the applicationof the first embodiment of the portable infusion pump unit illustratedin FIGS. 1-4 in a stationary charger and fixation system for providing astationary infusion pump system,

FIGS. 6 and 7 are schematic illustrations of a first embodiment of apump actuator according to the invention in two different positions,namely with the activating pin fully retracted in FIG. 6, and with theactivating pin fully extended in FIG. 7,

FIGS. 8 and 9 are schematic illustrations of a second and thirdembodiment, respectively, of a pump actuator according to the invention,

FIGS. 10-12 are schematic illustrations of three stages in the operationof a fourth embodiment of an actuator according to the invention,

FIG. 13 is a graph showing two curves of Contraction versus Force forshape memory alloy wires for different biasing systems for the actuatorsaccording to the invention, and

FIG. 14 is a graph showing the relationship between various forces inNewton and the distance of displacement of a piston pump plunger in mmby the actuator shown in FIGS. 10-12.

FIGS. 15 and 16 are schematic illustrations similar to FIG. 2 of asecond embodiment of an infusion pump unit according to the inventionillustrating the use of the shape memory alloy actuators of FIGS. 6-7and FIGS. 10-12, respectively, as the pump actuators

FIG. 17 is a sequence of schematic illustrations showing various stagesin the pumping cycle of a fluid pumping system according to theinvention utilising SMA actuators,

FIG. 18 schematically illustrates two stages in the operation of an SMAactuator incorporated in the pumping system in FIG. 17,

FIG. 19 is a schematic illustration of a first embodiment of a shapememory alloy actuator motor for use in an infusion pump according to theinvention,

FIG. 20 is a schematic illustration of a second embodiment of a shapememory alloy actuator motor for use in an infusion pump according to theinvention,

FIG. 21 is a schematic, partly sectional view of an infusion deviceaccording to the invention particularly well suited for dispensinginsulin to a diabetes patient,

FIG. 22 is a schematic view of the actuator and dispensing syringe ofthe device in FIG. 21,

FIG. 23 is a schematic view of a second embodiment of an actuator and adispensing syringe for incorporation in the device in FIG. 21

FIG. 24 is a schematic view of a rack-type SMA actuator forincorporation in the device in FIG. 21,

FIG. 25 is a perspective and schematic view illustrating an alternativeapplication of the first embodiment of the portable infusion pump unitillustrated in FIGS. 1-4 in a stationary charger and fixation system forproviding a stationary infusion pump system, and

FIG. 26 is a perspective and schematic view of the components of thesystem in FIG. 25.

In the drawings, a first embodiment of a portable infusion pump unit orapparatus is disclosed designated the reference numeral 10 in itsentirety. The apparatus 10 comprises a housing composed of twoshell-like housing parts 12 and 14 constituting a front and rear housingpart, respectively. The front an rear housing parts 12 and 14,respectively, are easily disassembled allowing the user to obtain accessto the interior of the apparatus for substituting an interior fluidpassage component to be described in greater detail below with referenceto FIG. 3 constituting a disposable pre-sterilized component which iseasily demounted after use and readily replaced prior to use. From therear side of the housing part 14, a clip 16 allowing the apparatus 10 tobe fixed to a strap or a belt extends. It is to be realised that termssuch as upper, lower, front, rear, etc., unless otherwise stated, in thepresent context define positions or orientations determined by theintentional application of the apparatus 10 as the apparatus ispositioned in an upright and substantially vertical position, e.g.received in the belt of a user by means of the clip 16 or otherwisepositioned exteriorly or non-implantatedly relative to the user.

In the front housing part 12, a display 20 is provided, comprising twosets of two digits designated the reference numerals 22 and 24,respectively, for displaying digits representing the time lapsed or thetime remaining for infusion operation expressed in minutes and hours,respectively, or seconds and minutes, respectively, or alternatively fordisplaying digits representing the supply of infusion liquid asexpressed in volume per time unit, e.g. ml per hour. The display 20further includes a display area 26 for informing the user and/or aperson operating the infusion pump apparatus 10 or nursing the userregarding the operational mode of the apparatus, such as standby orrunning information. Furthermore, the display 20 includes a number ofindividual displays positioned above one another and above thestandby/running display 26, one of which is designated the referencenumeral 28. These individual displays 28 are adapted to displayinformation such as the operational mode, e.g. the information that theapparatus is in a program mode, information regarding whateverinformation is presented on the two-digit displays 22, 24, such as thetime remaining for infusion operation, the total time of the infusionoperation, whether or not the apparatus is running or is to be started,or any other relevant information to be presented to the user oroperator. The display 20 further includes three individual alarmdisplays 30, 32 and 34 for informing the user of the presence of air inthe infusion pump circuitry, pressure fault or failure or low battery,respectively. A further display 36 informs the user or operator of theprogram sequence presently used or programmed, which program sequence isrepresented by a digit displaced by a 1-digit display 38. A 3-digitdisplay 40 of the display 20 represents information to the user oroperator regarding the infusion supply measured in ml per hour orsimilar relevant measure or ratio.

Below the display 20, a keyboard 42 is provided including a set of keys,one of which is designated the reference numeral 44 for allowing theuser/operator to control the portable infusion pump unit 10 to perform aspecific operation or to program the apparatus by shifting betweenspecific program sequences by increasing a specific digit displayed in a1-, 2- or 3-digit display, such as the displays 22, 24, 38 and 40, byincreasing or reducing the digit in question and by shifting a cursorroute relative to the various individual displays of the display 20 forallowing the user/operator to modify the operational mode or shiftbetween various preset programs of the apparatus.

At the one side wall of the housing, composed by the housing parts 12and 14 of the unit or apparatus 10, two terminals 46 and 48 are providedfor allowing the apparatus 10 to be connected to an electronic chargerfor supplying electric power to an internal rechargeable battery pack orcell of the apparatus. The terminals 46 and 48 may alternatively oradditionally serve as input/output terminals for establishingcommunication between the apparatus 10 and an external apparatus orequipment such as an external data logging apparatus or surveillanceapparatus or further alternatively for communicating with an externalprocessing unit such as a personal computer or data logging apparatus.Still further, the apparatus 10 may be provided with a conventionalinput/output terminal such as a conventional RS 232 terminal forestablishing communication between the apparatus 10 and an externalcomputer such as the above-mentioned personal computer for processingdata produced by the apparatus concerning the operational mode of theapparatus and also supplementary data produced by the apparatus orauxiliary equipment, e.g. data representing the temperature of theinfusion liquid supplied by the apparatus 10 or data supplied byadditional external measuring or surveillance equipment. In the top wallof the housing of the apparatus 10 two recesses are provided forreceiving two tube connectors 50 and 52 constituting a fluid inlet and afluid outlet, respectively, of the above-mentioned fluid passagecomponent to be described in further detail below with reference to FIG.3. As is evident from FIG. 2, a further fluid outlet 54 is provided inthe bottom wall of the housing of the apparatus 10 opposite to the fluidoutlet 52.

In FIG. 2, the interior structure of the portable infusion pump unit orapparatus 10 is disclosed, illustrating the fluid inlet 50 and the fluidoutlets 52 and 54. In FIG. 2, the reference numerals 56 and 58 designatetwo printed circuit boards including the electronic circuitry of theapparatus and including the display, the rechargeable power pack or cellcircuitry and the CPU-circuitry of the apparatus controlling the overalloperation of the apparatus including the infusion operation.Alternatively, the electronic circuitry of the apparatus may be includedin a single printed circuit board or, alternatively, three or moreprinted circuit boards. The internal re-chargeable battery pack or cellis designated the reference numeral 60.

In FIG. 2, the internal flow system of the portable infusion pumpapparatus 10 is disclosed, constituting a disposable and replaceablefluid passage component as mentioned above and including an inlet tube62 connected to the fluid inlet 50. Two capacitive detectors 64 and 66are mounted on the inlet tube 62 and communicate with the electroniccircuitry of the apparatus housed on the printed circuit board 56 and 58for detecting presence of air bubbles, if any, in the infusion liquidinput to the fluid inlet 50. At its output end, the inlet tube 62communicates with a first check valve 68 which constitutes an inlet to apump housing component 70, in which an internal fluid passage isprovided, as will be described in greater details below with referenceto FIG. 3, which fluid passage terminates in an output or second checkvalve 72 from which two branched-off outlet tubes 74 and 76 communicatewith the fluid outlets 54 and 52, respectively. For transferring theinfusion liquid or any other liquid input to the portable infusion pumpunit 10 through the fluid inlet 50 to an application site through one ofthe fluid outlets 52 and 54, a piston type pump actuator 78 is provided.The internal flow system of the portable infusion pump comprising thefluid inlet 50, the inlet tube 52, the capacitive detectors 64 and 66belonging to the inlet tube 62, the first check valve 68, the pumphousing component 70, the output check valve 72, the outlet tubes 74 and76, and the outlets 52 and 54 constitute an integral disposable andreplaceable fluid passage component to be described in greater detailbelow with reference to FIG. 3.

In FIG. 3, the interior of the check valves and also the pump housingcomponent 70 is disclosed in greater detail. The first check valve 58basically comprises a central circular cylindrical housing component 80from which a frusto-conical top part 81 extends upwardly communicatingwith the inlet tube 62 and arresting an inlet filter element 82 at thetransition between the frusto-conical top part 81 and the cylindricalhousing component 80. The cylindrical housing component 80 comprises acentral annular oral component 84 which is sealed off in the initial ornon-active position by a downwardly deflectable sealing membrane 86.Provided the pressure below the sealing membrane 86 is lower than thepressure above the membrane 86, the membrane 86 is forced downwardlyallowing liquid to pass through the central aperture of the centralannular component 84 and further through apertures 87 provided offsetrelatively to the centre of the sealing membrane 86.

The first check valve 68 communicates with an inlet passage 88 of thepumping house component 70 terminating in an inner chamber definedwithin an upwardly protruding annular top housing component 90 in whicha reciprocating plunger 94 of the piston pump actuator 78 is movable inthe direction to and from an abutting pin 96 which separates the inletpassage 88 from an outlet passage 98. The interspace between thereciprocating plunger of the piston pump 78 and the inner surface of theannular top housing component 90 is sealed by means of a highly flexiblesealing gasket 92.

The outlet passage 98 communicates with the above described second checkvalve 72 which is basically of a configuration similar to andfunctioning as a check valve similar to the above described first checkvalve 58, however differing from the above described first check valvein that the second check valve 72 does not include any filter elementsimilar to the filter element 82. The second check valve 72 includes adownwardly protruding annular housing part 100, which is cast integralwith the pumping house component 70, fulfilling, however, the samepurpose as the above described annular housing part 80 of the firstcheck valve. From the annular housing part 100, a downwardly protrudingfrusto-conical housing part 101 similar to the above describedfrusto-conical housing part 81 extends communicating with the outlettube 74 and similarly the outlet tube 76 described above with referenceto FIG. 2. Within the annular housing part 100, a sealing membrane 102similar to the above described sealing member 86 is received, whichincludes apertures 103 similar to the apertures 87 described above. Thesealing membrane 102 communicates with a conical bore 99 communicatingwith the outlet passage 98 for sealing off communication from the outletpassage 98, through the conical bore 99 to the outlet tube 74 providedthe sealing membrane 102 rests against an abutting lower surfacedefining the lower boundary of the conical bore 99.

The pumping operation of the portable infusion pump unit 10 isestablished as follows. Initially, the first check valve 68 and thesecond check valve 72 are in their initial and sealing positions. It isalso assumed that liquid is present within the inlet tube 62 within theinlet passage 88 and the outlet passage 98 and also within the outlettube 74. The piston pump actuator 78 is activated through the supply ofan electric signal such as an alternating electric signal or a pulsedsignal causing the reciprocating plunger 94 to move upwardly ordownwardly. The piston pump actuator 78 will be described in greaterdetail below with reference to FIGS. 6-12. The plunger 94 is presseddownwardly in relation to the orientation of the piston pump actuator 78shown in FIG. 3.

Assuming that the first movement of the reciprocating plunger 94 is inmovement upwardly, a relative vacuum is created within the inlet passage88 and the outlet passage 98 by the increase of the volume defined belowthe sealing gasket 92.

Through the creation of the relative vacuum within the inlet passage 88,the first check valve 68 is operated as the downwardly deflectablesealing membrane 86 is caused to move downwardly allowing liquid to flowinto the inlet channel 88 through the central aperture of the centralannular component 84 as described above. At the same time, the relativevacuum within the outlet passage 98 creates a relative vacuum above thesealing membrane 102 which is biased so as to prevent free flow throughthe second check valve 72 urging or forcing the sealing membrane intosealing off and abutting engagement with a wall part circumferentiallyencircling and defining the conical bore 99, and consequently preventingliquid from being transferred from the outlet passage 98 to the outlettube 74. In summary, during the raising of the reciprocating plunger 94,the first check valve 68 is activated and caused to open whereas thesecond check valve 72 is blocked.

As the reciprocating plunger is moved downwardly, a relative increasedpressure is created within the inlet passage 88 and the outlet passage98 and the operations of the first and second check valves are shiftedas the relative increased pressure within the inlet passage 88 causesthe first check valve 68 to block and seal off whereas the increasedpressure within the outlet passage 98 causes the second check valve 72to open allowing the fluid present within the outlet passage 98 to beforced out through the conical passage 99, through the apertures 103 ofthe sealing membrane 102 and further into the outlet tube 74. The rateof transfer and consequence the flow of liquid from the outlet tube 74is controlled by the rate of operation of the piston pump actuator 78 asan increased frequency of reciprocating the reciprocating plunger 94increases the velocity of flow of fluid or liquid from the inlet tube 62to the outlet tube 74.

Above the second check valve 72, a bypass valve is provided, comprisinga sealing membrane 104 which is acted upon by a central stem element 106of a turnable knob 108 so as to force the sealing membrane 104 intosealing off and abutting engagement with a conical bore 105 providedabove and in registration with the above described conical bore 99.Provided the conical bore 105 is sealed off by means of the sealingmembrane 104, the bypass valve is not in operation. Provided the sealingmembrane 104 is raised from its sealing off and abutting engagement withthe conical bore 105 as the knob 108 is rotated for causing elevation ofthe actuator stem 106, communication from the outlet passage 98 isestablished through a bypass passage 110, bypassing the communicationfrom the outlet passage 98 through the conical passage 99 for allowingfluid to flow from the outlet passage 98 through the bypass passage 110and further through the apertures 103 of the sealing membrane 102 whichis consequently not functioning as the bypass valve is in operation.

The piston pump actuator 78, which may constitute a replaceablecomponent of the portable infusion pump unit or apparatus 10, mayprovide a specific stroke and, consequently, a specific flow volume perstroke. Therefore, the actuator 78 is preferably provided with a switchcooperating with a switch of the electronic circuitry of the apparatusfor informing the microprocessor of the electronic circuitry of theapparatus of the type of piston pump actuator included within theapparatus at present. The technique of providing information to themicroprocessor concerning the type of piston pump included within theapparatus at present may be established by means of numerous techniqueswell-known in the art per se such as by means of code switches, opticcapacitive or inductive readers, or simply by means of a feedbackcircuit monitoring the work rate of the piston pump actuator.

In FIG. 3, an inlet tube 112 is shown establishing communication fromthe inlet tube 62 through the fluid inlet 50 not shown in FIG. 3,however, shown in FIG. 2 from an infusion bag 114 which may constitutean infusion bag including an infusion liquid simply constitutingphysiological liquid or additionally or alternatively a drug suspendedin any appropriate liquid, or alternatively blood plasma. The outletfrom the outlet tube 74 of the portable infusion pump unit 10 shown inFIG. 4 is connected to an outlet tube 116 through the fluid outlet 54,not shown in FIG. 3, however, shown in FIG. 2, which external outlettube 116 communicates with a cannular assembly 118 of a basicallyconventional structure.

The inlet tube 112 and the outlet tube 116 may constitute separate inletand outlet tubes to be connected to the infusion pump unit 10 throughthe inlet and outlet 50 and 52 or, alternatively, 54, respectively.Alternatively, and preferably, the inlet tube 112 and the outlet tube116 constitute integral components of the disposable and replaceablefluid passage component illustrated in FIG. 3, which fluid passagecomponent is cooperating with and activated by means of the piston pumpactuator 78. Further alternatively, the infusion bag 114 may beconfigurated and housed within a container component which isconfigurated so as to allow the infusion bag 114 to be received andsupported on top of the infusion pump unit or apparatus 10 as theabove-mentioned receiver is simply connected to and supported by thehousing of the portable infusion unit or apparatus 10.

The infusion of liquid from the infusion bag 104 is further illustratedin FIG. 4, in which the portable infusion pump 10 is received and fixedrelative to an individual 120 by means of a belt or strap 122 on whichthe infusion bag 114 is further fixated. In FIG. 4, the external inlettube 112, the external outlet tube 116 and the cannular assembly 118 arealso illustrated.

In FIG. 5, the above described first embodiment of the portable infusionpump unit or apparatus 10 is shown in duplicate received within astationary receptor 140 in which a plurality of receptor compartments142 are defined. Each of the receptor compartments 142 is provided witha set of charger terminals for establishing electrical conductivecommunication with the charger terminal 46 and 48 of the apparatus orunit 10 received within the receptor compartment 140 in question forcharging the internal rechargeable battery pack or cell of the apparatusor unit through the supply of electric energy from a mains power supplyunit of the receptor assembly 140 which mains supply power supply unitreceives electric power through a coiled mains supply wire 148terminating in a mains plug 150 which is received in a mains AC outletsocket 152.

The receptor assembly 140 further includes a set of indicator lamps 144and 146. Provided none of the indicator lamps 144 and 146 correspondingto a specific receptor compartment 142 are turned off, the indicationinforms the user or operator that no charging is taking place in thereceptor compartment in question. Provided a portable infusion pump unitis received within a specific receptor compartment 142, one of the lamps144 and 146 corresponding to the receptor compartment is turned off, oneof which informs the user or operator that the potable infusion pumpunit in question is to be recharged, or alternatively the other lamp isturned on informing the user or operator that the portable infusion pumpunit in question is fully charged and ready for use. Alternativeinformation display modes, such as flashing of lamps for informingmalfunction in the rechargeable battery pack or cell of the portableinfusion pump is of course also readily deduceable.

In connection with infusion pumps, particularly portable medicinalinfusion pumps, it is important that the pumping action be carried outby a very compact actuator functioning as quietly as possible, with aslow energy consumption as possible and with as small a waste heatproduction as possible.

The pump actuator 78 in FIGS. 2 and 3 is, according to the invention, ashape memory alloy actuator which embodies all the above desirablecharacteristics. Several shape memory alloy actuators for use as a pumpactuator in medicinal infusion pumps will be described in following, itbeing understood that these actuators are particularly useful as thepump actuator 78 in FIGS. 2 and 3.

Referring now to FIGS. 6 and 7, a pivotable body in the form of acircular disc 1′ is arranged for pivoting around a central pivot 2′fixedly attached to a not shown frame of the actuator, and the disc 1′is provided with a peripheral extension 3′ and a yoke-like peripheralextension 5′. A tension coil spring 6′ is at one end thereof pivotablyattached to a fastening pin 7′ fixedly attached to said frame and is atthe other end thereof pivotably attached to a fastening pin 8′ fixedlyattached to the peripheral extension 3′.

Two wires or filaments 9′ and 10′ of a shape memory alloy such as nickeltitanium alloy or nitinol, for instance supplied by the companyDYNALLOY, INC, of Costa Mesa, Calif., USA, under the trade nameFLEXINOL, are attached at one end thereof to electrically conductiveterminals 11′ and 12′, respectively, fixedly attached to said frame.

The other end of each of the wires 9′ and 10 is attached to anelectrically conductive terminal 13′ fixedly attached to the peripheryof the disc 1′. The wires 9′ and 10′ extend along the periphery of thedisc 1′ such that the wires 9′ and 10′ when tensioned extend along andare supported by said periphery. In the drawings the wires 9′ and 10′are shown spaced from said periphery for the sake of clarity.

A sliding body 14′ having two arms 15′ and 16′ is arranged for slidingmovement between two stop pins 17′ and 18′ attached to the frame. A pin19′ attached to the sliding body 14′ is received in the fork 5 a′ of theyoke-like extension 5′ such that the pin 19′ may slide and rotate freelyin the fork when the disc 1′ pivots from the position shown in FIG. 6 tothe position shown in FIG. 7 thereby slidingly displacing the body 14′from abutment against stop pin 18′ to abutment against stop pin 17′ withthe arm 15′, constituting the activating pin of the actuator, fullyextended.

A proximity sensor 20′ is attached to the frame and connected to notshown electrical conductors for transmitting a signal from the sensor toa not shown receiver. The terminals 11′ and 12′ are likewise eachconnected to an electrical conductor, not shown, connected to a notshown power source for supplying electrical power to the wires 9′ and10′ for resistance heating thereof, the terminal 13′ being likewiseconnected to the not shown power source through a not shown electricalconductor for closing the resistance heating circuit.

In use, the wires 9′ and 10′ are intermittently heated to thetransformation or transition temperature (from martensitic to austeniticstate) of the shape memory alloy which temperature for nitinol isapproximately 90° C. Thereby the length of the wire is shortened. Whenthe wire cools to below 90° C. the length thereof reverts to normal,i.e. the wire lengthens. The speed at which the shortening takes place,i.e. the contraction time, is directly related to the current input.i.e. the voltage applied over the terminals 11′ or 12′ and 13′.

In the position depicted in FIG. 6, the intermediate disc 1′ is in itsoutermost counter clock-wise position with the arm 15′ fully retractedand with the wire 9′ cooled to below 90° C. and the wire 10′ heated toabove 90° C. by applying an electrical voltage between the terminal 12′and 13′ whereby an electrical current will flow through the wire 10′.The disc 1′ has therefore been rotated counter clock-wise to theposition shown by the contraction force exerted by the wire 10′.

In the next step, the wire 10′ is cooled to below 90° C. and therebylengthens to the shape indicated by the dotted line 10 a′ in FIG. 6. Theactuator is now ready to perform an activating extension of the arm 15′towards the left, the end of the arm 15′ being intended to come intocontact with a not shown plunger 94 and depress or activate same duringthe movement of the arm 15′ to the extended leftwards position thereofas depicted in FIG. 7.

Thereafter or simultaneously, the wire 9′ is heated to above 90° C.whereby it contracts and exerts a clock-wise force on the disc 1′pivoting it clock-wise around the pivot 2′ past the balance position ofthe disc 1′ and spring 6′ in which the attachment pins 7′ and 8′ of thespring 6′ are aligned with the pivot 2′.

When the disc 1′ has rotated clock-wise past said balance point, thetension force exerted by the spring 7′ will continue the clock-wiserotation of the disc 1′ to the position shown in FIG. 7 with the arm 15′fully extended and the wire 9′ slack though still above 90° C. This isthe actual activating movement of the actuator where the force appliedto the sliding body 14′ by the extension 5′ increases because of theincreasing lever of force or moment arm of the tension force exerted bythe spring 6′ on the intermediate disc 1′ with respect to the pivot 2′or axis of rotation of the disc 1′.

For applications where the force necessary to perform the function ofthe actuator, such as depressing the pump plunger 94 in FIG. 3,increases during the activating stroke, said increase of the springforce moment arm as the disc 1′ rotates is a very advantageous featureas will be explained more in detail in connection with FIGS. 13 and 14in the following.

An increase of the activating force of the actuator during theactivating stroke is also achieved or enhanced by decreasing thedistance of the pin 19′ from the pivot 2′ or axis of rotation of thedisc 1′ during the activating stroke whereby the moment arm or lever offorce of the displacement force exerted on the pin 19′ by the yoke-likeextension 5′ with respect to the pivot 2′ is decreased and thereby thedisplacement force is increased during the activating stroke. Thisshortening of said distance can be seen from the situation in FIG. 6 atthe beginning of the activation stroke to the situation in FIG. 7 at theend of the activation stroke.

Finally, the wire 10′ is heated above 90° C. so that it contracts andpivots the disc 1′ back to the position shown in FIG. 6 whereby theactivating cycle is ready to be repeated.

The length of the wire 10′ is larger than the length of the wire 9′because the contraction or shortening of the wire 10′ must be largeenough to pivot the disc 1′ from the position shown in FIG. 7 past thebalance point mentioned above while the shortening of the wire 9′ onlyhas to be enough the pivot the disc 1′ from the position shown in FIG. 6past said balance point.

Nitinol wires will typically contract about 3%-6% when heated past thetransition temperature. The uncontracted length of the wire 10′ shouldbe enough to ensure that the uncontracted wire is fully extended in theposition shown in FIG. 7 and that the contracted wire 10′ is fullyextended when the disc 1′ is at least slightly past said balance pointin the counter-clockwise direction, i.e. the uncontracted length of wire10′ should be about 22-25 times the distance of travel of terminal 13′between the FIG. 7 position thereof and the balance point positionthereof.

The necessary contraction force to be exerted by wires 9′ and 10′ arerather different because the contraction force of wire 9′ only has tocounteract the torque or moment of the spring force of spring 6′ withthe relatively small torque arm in FIG. 6 while the contraction force ofwire 10′ has to counteract the considerably larger torque of said springforce in FIG. 7. The contraction force of a nitinol wire is larger thelarger the diameter or cross sectional area of the wire. The crosssectional area of wire 10′ is thus considerably larger than the crosssectional area of wire 9′ or there may be a number of wires 10′ with thesame cross sectional area.

The latter possibility is chosen if it is necessary that the cooling-offtime for the wires 10′ is as short of possible so that the intervalbetween the activating cycles may be as short as possible. Several smalldiameter wires with a certain total cross sectional area will cool morerapidly than a single larger diameter wire with the same cross sectionalarea.

The signal emitted by the proximity sensor 20′ each time the extension3′ is in the position shown in FIG. 7 may be utilised for many differentpurposes such as for instance a mere monitoring of the correct functionof the actuator or for controlling the timing of the heating of thewires 9′ and 10′ and thereby the timing of the activating stroke of thesliding body 14′. Naturally, the location of the proximity sensor or ofany other type of sensor for sensing the position of the disc 1′ may bevaried according to the purpose thereof, and several such sensors may beprovided in different locations for instance for achieving a morecomplex control of the timing of the activating effect of the actuator.

Referring now to FIG. 8, this embodiment differs from the embodiment ofFIGS. 6-7 in that a double activating effect may be achieved for eachcycle of heating and cooling the shape memory wires 21′ and 22′ that inthis case are of equal length and cross sectional area. The rotation ofthe disc 1′ counter-clockwise and clockwise is limited by stop pins 23′and 24′, respectively.

The activating member may be a sliding body similar to body 14′ in FIG.6-7 where both the arm 15′ and the arm 16′ perform an activatingfunction, or the activating function may be a pull/push activation byfor instance arm 15′.

The disc 1′ may alternatively be provided with a central torsion shaftprojecting at right angles to the plane of the disc 1′ as a prolongationof the pivot 2′ such that the torsion shaft functions as the activatingmember by for instance rotating a lever to and fro. Many different typesof activating members connected to the disc 1′ will be obvious to thoseskilled in the art.

In the position shown in FIG. 8, the disc 1′ has just performed anactivating rotation counter-clockwise under the influence of thecounter-clockwise torque of the force of the spring 6′ and is ready forthe initiation of a rotation clockwise by heating the wire 21′ so thatthe disc 1′ is rotated against the counter-clockwise torque of thespring force until the balance point is passed. Then the activatingrotation clock-wise is performed by the clock-wise torque of the springforce. Also in this embodiment the moment arm of the activating force ofthe spring 6′ increases during the activating stroke in both directions.

Referring now to FIG. 9, the terminal 13′ of the embodiments of FIGS.6-8 has been substituted by a combined terminal and abutment member 28′for abutting the stop pins 24′ and 25′. Furthermore, another type ofbiasing means is utilized, namely a piston and cylinder mechanismcomprising a pressurized cylinder 24′ pivotably attached to pin 7′, apiston 26′ and a piston rod 27′ pivotably attached to the disc 1′ bymeans of a pin 27′.

The piston and cylinder mechanism 24′-25′ functions like a compressionspring and could in fact be substituted by a compression spring. In FIG.9 the disc 1′ is in the balance point position where the pin 7′, the pin27′ and the pivot 2′ are aligned such that the pressure exerted on thedisc 1′ by the piston rod 25′ does not produce any torque on the disc1′. In the situation shown in FIG. 9, the wire 22′ is contracting androtating the disc counter clock-wise past the balance point. As soon asthe balance point has been passed, the torque from the piston rod 25′will cause the activating counter clock-wise rotation of the disc 1′until the member 28′ abuts the stop pin 23′ whereupon a clockwiserotation may be initiated in a manner very similar to that describedabove in relation to FIG. 8.

The tension spring 6′ in FIGS. 6-7 could also be substituted by a pistonand cylinder mechanism or a compression spring in an arrangement similarto FIG. 9.

Referring now to FIGS. 10-12 an activating body 30′ is arranged linearlydisplaceable in the directions of arrows R1 and R2 under the influenceof a shape memory alloy wire 31′ and a two-armed lever 32′.

One end of the wire 31′ is attached to the body 30′ at 33′ and the otherend is attached to a fixed portion 37 a′ of a not shown frame of theactuator, the wire 31′ extending around a pulley 34′ pivotably arrangedon a slide 35′ displaceable in the directions of the arrows R1 and R2. Acompression spring 36′ is arranged between the body 30′ and the slide35′ and extends through a passage through a fixed portion 37′ of saidframe.

The two-armed lever 32′ is arranged pivotable around a pivot 38′, onearm 39′ of the lever abutting a pin 40′ on the body 30′ and the otherarm 41′ of the lever being attached at 42′ to one end of a tensionspring 43′, the other end being attached to a fixed portion 44′ of saidframe such that displacement of the body 30′ in the direction of arrowR1 tensions the spring 43′ via rotation of the intermediate lever 32′.

A pawl or hook element 45′ is arranged pivotable around a pivot 46′ suchthat a hook or projection 47′ of the hook element 45′ may be received ina matching recess 48′ in the body 30′. A shape memory alloy wire 49′ isat one end attached to the hook element 45′ and at the other endattached to a fixed portion 50′ of said frame. A compression spring 51′is arranged between the fixed portion 50′ and the hook element 45′

In use, the body 30′ is moved to and fro in the direction of the arrowsR1 and R2 to activate the plunger 94 during the activating stroke of thebody in the direction R1.

In FIG. 10 the wire 31′ is cooled to below the transformationtemperature of the alloy (for instance by sandwiching the wire betweentwo aluminum rails coated with PTFE) and is at its maximum length and ismaintained taut by the biasing action of the compression spring 36′. Thehook 47′ is received in the recess 48′ and holds the body 30′ againstthe biasing force of the spring 43′ transmitted to the pin 40′ by meansof the lever 32′. The wire 49′ is also in its cool state and at itsmaximum length.

When the activating stroke is to be initiated, the wire 49′ is heated tothe transformation temperature and shortens or contracts, therebypivoting the hook element 45′ against the biasing force of the spring51′ such that the hook 47′ is pulled out of the recess 48′ to therelease position shown in FIG. 11. The body 30′ is thus released fordisplacement in direction R1 under the influence of the lever 32′pivoted by the spring 43′.

During the activating stroke of body 30′ in direction R1 the lever ormoment arm of the force exerted by the spring 43′ relative to the pivot38′ or the axis of rotation of the lever 32′ increases such that thedisplacement force exerted on the pin 40′ by the arm 39′ increases asthe body 30′ is displaced in the direction R1.

Likewise, during the activating stroke by the body 30′ in direction R1,the lever or moment arm of the displacement force exerted by the arm 39′on the pin 40′ relative to the pivot 38′ decreases whereby saiddisplacement force increases as the body 30′ is displaced in thedirection R1.

When the slide 35′ abuts the fixed frame portion 37′, the activatingstroke in direction R1 will be stopped as shown in FIG. 11. In practicethe activating stroke preferably is stopped by the resistance to theactivating stroke of the body 30′ by the plunger 94 being activated suchthat the stroke is stopped before the slide 35′ abuts the fixed frameportion 37′.

So as to cock the actuator again, the wire 49′ is cooled to allow thespring 51′ to pivot the hook element 45′ towards the holding positionthereof while the wire 31′ is heated until it shortens and therebycauses the slide 35′ to abut the fixed frame portion 37′ and the pulley34′ to rotate clock-wise while the body 30′ is displaced in thedirection R2 against the force of the spring 43′ that thereby islengthened while the lever 32′ pivots counter clock-wise. When the body30′ has reached the position shown in FIG. 12, the hook 47′ is pressedinto the recess 48′ and the wire 31′ may then be cooled so that thesituation in FIG. 10 is re-established ready to initiate a newactivation cycle of the actuator.

During the tensioning of the spring 43′, the force exerted by the wire31′ necessary for this tensioning is largest at the beginning of thedisplacement of the body 30′ in the direction R2 because of the largemoment arm of the force of the spring 43′ and the small moment arm ofthe rotation force of the pin 40′ on the arm 39′, and the force exertedby the wire 31′ decreases as the body 30′ is displaced in the directionR2. This is an advantageous development of the force in the wire 31′during the cocking of the actuator as will be explained more in detailin the following in connection with FIGS. 13 and 14.

By adapting the actuator according to the invention such that theactivating stroke is performed by a force exerted by a biasing means, afurther advantage is obtained in that any blocking of the activatingstroke of the activating body, for instance because the pump plunger 94is blocked, will only entail that the activation stroke is stopped withno damage to the SMA wire. If the activating stroke were carried outunder the influence of a shortening of a shape memory alloy wire, saidwire would probabaly be damaged or snapped if the activating stroke wereblocked.

The extra length of the wire 31′ obtained by means of the pulley 34′ isadvantageous for giving a longer activating stroke with a compactconstruction of the actuator.

The heating of the wires 31′ and 49′ is carried out in a manner similarto the heating of the wires 9′ and 10′ in FIGS. 6-7 by means of notshown electrically conductive connections of the ends thereof to thebattery pack 60 of the infusion pump unit according to the invention.

Referring now to FIG. 13, the curve or line 80′ indicates therelationship between the force exerted by an SMA wire on a body in onedirection while the body id biased by a tension spring in the oppositedirection as a function of the contraction or shortening thereof. Theforce increases proportionally with the contraction because of theproportional increase of the spring force of the spring when it isstretched by contraction of the wire.

The line or curve 81 is symbolic of the curves corresponding to therelationship between contraction and force exerted for the embodimentsof FIGS. 6-9 where the force in the wires 10′, 22′, 24′ and 31′,respectively is largest at the beginning of the contraction orshortening, and the contraction length of the wire is much largerbecause of the variation in the length of the moment arm or arms duringthe activating stroke as described above.

In this manner, a high coefficient of mechanical efficiency is obtainedbecause the longer contraction distance for a given input of energy toheat the SMA wires gives an increased input of energy into theactivating system.

The actual curves 81 will not be linear but will reflect the varyingrate of change of the moment arm or moment arms during the activatingstroke.

Referring now to FIG. 14 and FIGS. 10-12, an actuator as shown in FIGS.10-12 is applied to depress the plunger 94 of the infusion pump in FIG.3 thereof with the body 30′.

The plunger 94 and body 30′ travel from 0.2 mm to 3.4 mm during theactivating stroke of the body 30′. The force required to displace theplunger increases substantially proportionally from approx. 0.5 N toapprox. 2N where the force increases steeply because the plunger hasreached the end of its path.

The force exerted by the spring 43′ on the body 30′ and thus the plunger94 develops as an increasing parable-like curve corresponding to thecurve for the tension or force in the SMA wire 31′ necessary to retractthe body 30′ against the leveraged force of the spring 43′.

It is clear that the curves show that the actuator according to theinvention can produce an increasing force as the displacement increaseswhich is very advantageous in applications such as pumping with pistonpumps where the force required increases with the distance traveled bythe plunger.

Referring now to FIGS. 15 and 16, the infusion pump unit 10 is verysimilar to the infusion pump unit 10 of FIG. 2, the sole differencebeing the location of the print cards 56 and 58. The actuators of FIGS.6-7 and 10-12 are utilized as the pump actuator 78 in FIG. 15 and FIG.16, respectively. The SMA wires are supplied with electrical current forheating by the battery pack 60

The SMA actuators of FIGS. 6-7 and 10-12 are particularly well-suitedfor depressing the pump membrane 92 (see FIG. 3) as the force needed forthis operation increases as the membrane is depressed and the fluid ispressed out into the conduit 98. Furthermore, the operation of the SMAactuators is very quiet and the energy consumption is low while thespace requirements are limited and the weight low.

As an example the SMA wire 31′ of the SMA pump actuator of FIG. 16 issupplied with 4 amperes during 4 milliseconds for each pump depressioncycle, and the maximum number of depression cycles for the infusion pumpis normally of the order of magnitude of 10,000 cycles/hour.

Referring now to FIGS. 17 and 18, a fluid pumping system 60′ comprises aflexible tube 61′ extending through or between at least three clampingdevices 62′-64′ arranged adjacent one another. As illustrated in FIG. 18the clamping devices each comprise a pivotable jaw 65′ that is arrangedto pivot towards a fixed jaw 66′ to flatten the tube 61′ extendingbetween the jaws 65′ and 66′ and to pivot away from the fixed jaw 66′ toallow the tube 61 to return to its natural open shape.

Each of the pivotable jaws 65′ is attached to one end of a biasing meanssuch as a tension spring 67′ the other end of which is attached to afixed portion 68′ of a not shown frame. Each of the pivotable jaws 65′is furthermore attached to one end of a shape memory alloy wire 69′ theother end of which is attached to a fixed portion 70′ of said frame. Thejaws 65′ are held in the closed position against jaw 66′ by the springs67′ with the tube 61′ flattened while shortening or contraction of theSMA wires 69′ opens the clamping devices by pivoting the jaws 65′ awayfrom the fixed jaw 66′.

The pumping action is achieved by the sequence indicated from left toright in FIG. 17, all three clamping devices 62′-64′ being clamped shutin the first stage from the left with all three wires 69′ cooled tobelow the transition temperature and therefore slack.

In the second stage from the left devices 63′ and 64′ are opened byheating the corresponding wires 69′ to above the transition temperaturewhereby fluid enters the thus opened portion of the tube 61′ asindicated by arrow R5.

In the third stage from the left device 64′ is clamped shut by coolingthe corresponding wire 69′ such that the corresponding spring 67′ canpull the corresponding jaw 65′ against the tube 61′ flattening it.Hereby a portion of fluid is trapped a space 71′ in the tube 61′.

In the fourth stage from the left, the device 61′ opens while the device62′ closes whereby the portion of fluid trapped in the space 71′ isforced to flow in the direction of arrow R6 whereafter device 61′ isclosed and the first stage from the left has been re-established tobegin a new pumping cycle.

If more than three clamping devices are utilized, the pumping effectwill be enhanced.

This “finger” pump may substitute the pumping system in FIGS. 3, 15 and16 as well as the check valves 68 and 72, and the pumping system (tube61′) may still be replaced without replacing the pump actuator bythreading the tube 61′ from between the jaws 65′ and 66′. Thereby anextremely cheap replaceable pump is provided.

The pivoting of each of the jaws 65′ of the clamping devices 62′-64′towards the fixed jaw 66′ may be achieved by means of a body 15′ of theactuator in FIG. 6 or a body 30′ of the actuator in FIG. 5.

The tube 61′ may alternatively be flattened directly by said bodies 15′or 30′ without the use of a clamping device. Hereby, a particularlysimple pumping system is achieved where the replacement of the tube 61′is particularly simple.

Referring now to FIG. 19, a toothed wheel or gear 55″ is rotatablyarranged on a power output shaft 56″ journalled in a not shown frame ofthe actuator motor. A body 57″ having an edge portion 58″ fittingbetween two neighbouring teeth 59″ of the gear 55″ is arranged in saidframe displaceable between the position shown in full lines and theposition shown in dotted lines.

A shape memory alloy wire 60″ is at one end attached to the body 57″ andat the other end to a fixed portion 61″ of said frame. A coiled flat orwire spring 62″ integral with or connected to an arm 63″ is attached tosaid frame such that said arm 63″ may pivot around one end thereofopposite the free end thereof. The arm 63″ abuts a pin 64″ on the body57″.

A pawl 65″ is pivotably arranged on a pivot 66″ and is biased by atension spring 67″ so as to constantly abut the rim of the gear 55″.

In use, the gear 55″ is turned clock-wise by the body 57″ beingdisplaced from the full line position to the dotted line positionthereof by the force of the spring 62″ acting through the intermediatearm 63″ on the pin 64″, whereby the gear advances the width of one tooth59″ and the pawl 65″ moves from locking engagement between one pair ofteeth 59″ to a locking position between the next pair of teeth in thecounter clock-wise direction.

When the gear is locked against rotating counter clock-wise by the pawl65″, the SMA wire 60″ is heated and shortens whereby the body isdisplaced from the dotted line position to the full line positionagainst the force of the intermediate arm 63″ on the pin 64″ therebycocking the spring 62″.

The lever or moment arm of the displacement force exerted by theintermediate arm in the clock-wise direction with respect to thepivoting point of the arm decreases as the body is displaced in theactivating direction from the full line position to the dotted lineposition whereby the displacement force exerted by the intermediate arm63″ on the pin 64″ increases.

Referring now to FIG. 20, a SMA actuator motor similar to the motor ofFIG. 19 is shown, the spring 62″ and intermediate arm 63″ beingsubstituted by a tension spring 68″ fastened to the body 57″ and to afixed portion 69″ of a not shown frame.

The operation of the motor of FIG. 20 is very similar to the one in FIG.19 except that the displacement force exerted on the body 57″ by thespring 68″ is exerted directly and declines substantially proportionallywith the distance of displacement.

Referring now to FIG. 21, an infusion pump 70″ particularly well suitedfor infusing insulin to a diabetes patient comprises a housing 71″containing a display 72″, on/off buttons 73″, print cards 74″ and a notshown battery pack. These elements will not be described further as theyare well known to those skilled in the art and may vary greatly withinthe scope of the invention as defined by the appended patent claims.

A dispensing cartridge, ampoule or syringe 75″ is replaceably arrangedin the housing 71″ and has an outlet nozzle 76″ for communication with anot shown conduit means connected to the patient for delivering thefluid, preferably insulin, in the syringe 75″ to said patient in acontrolled manner either continuously or according to a pre-determinedsequence.

A piston 77″ is slidably arranged in the syringe 75″. A threaded rod orspindle 78″ abuts the piston 77″ for displacing it towards the outletnozzle 76″ and meshes with a gear 79″ meshing with a pinion 80″ rotatedby a shape memory alloy motor for displacing the spindle 78″ towards theoutlet nozzle 76″.

Referring now to FIG. 22, the SMA motor of FIG. 20 is shown arranged andadapted for rotating the pinion 80″ such that rotation of the gear 55″is geared down to a much slower rotation of the spindle 78″ so as todispense the liquid or paste in the syringe 75″ in very small amounts.

The SMA motor of FIG. 19 may very advantageously replace the motor ofFIG. 19 in the configuration of FIG. 22 because of the reversecharacteristic of the spring 62″ compared to the characteristic ofspring 68″ as discussed in connection with FIGS. 13 and 14.

Referring now to FIG. 23, a different embodiment of the piston operationis illustrated, a double headed piston 81″ being displaced by an arm 82″mounted on a carrier block 83″ rotatably mounted on a spindle 84″ suchthat rotation of the spindle 83″ displaces the block 83″, arm 82″ andpiston 81″ towards the nozzle 76″ for expelling liquid or paste in thesyringe 75″.

The spindle meshes with a gear 85″ meshing with a pinion 86″ attached tothe shaft 56″ of the SMA motor of FIG. 19, the spring 67″ not beingshown for the sake of clarity.

Referring now to FIG. 24, a rack 70″′ is arranged displaceable in a notshown frame in the direction R4 and a body 71″′ is arranged displaceablein the directions R3 and R4 as well as transversly thereto. A SMA wire72′″ is attached to the body 71′″ and to a fixed portion 73′″ of saidframe. A coil spring 74′″ attached to said frame and integral with orconnected to an intermediate arm 75′″ exerts a displacement force on apin 76′″ of the body 71′″ through the intermediate arm 75′″ in a mannervery similar to spring 62″ in FIG. 19.

The rack 70′″ advances the distance of the width of one tooth 78′″thereof in the direction R4 for every cycle of heating and cooling ofthe SMA wire 72′″ in the same way as gear 55″ in FIG. 19 is rotated bywire 60″, spring 62″, intermediate arm 63″ and body 57″ in FIG. 19.

The rack 70″ may be used to push the piston 77″ in FIG. 22 or piston 81″in FIG. 23 by means of front end 77′″, to empty said cylinder of liquidor paste through an aperture in said cylinder.

Referring now to FIGS. 25 and 26, an optional number of infusion pumpunits 10 with corresponding inlet tube 112 and infusion bag 114 may beaggregated in a system of individual dockiing stations 100′ arranged ona not shown standard hospital rack allowing horizontally adjustablelocation of the docking stations 100′ that such two or more stations maybe aligned abutting one another as shown in FIG. 25.

A power distribution and computer connection box 101′ having connections102′ to a power source and a computer is also adapted for abutting adocking station 100′ in aligned configuration therewith.

The distribution box 101′ has a number of female contact plugs 103′ formating with corresponding, not shown, male contact plugs in a lateralwall of a docking station 100′. A diode 101 a′ indicates whether thedistribution box is functioning or not. Each docking station has anumber of female contact plugs 104′ in the opposite lateral wallidentical to contact plugs 103′ for mating with said not shown malecontact plugs of an adjacent docking station 100′.

The female and male contact plugs distribute electrical energy to theindividual docking station and to the individual infusion pumps 10docked in the docking stations 100′ via female contact plugs 105′ matingwith not shown corresponding male contact plugs in the bottom of eachinfusion pump 10.

Each infusion pump 10 is carried by a carrying frame 106′ between arms107′ thereof and supported on a bottom platform 108′ thereof. A hook109′ is provided on the carrying frame 106′ for hooking into an aperture110′ of the infusion bag 114. The frame 106 furthermore has a topaperture 111′ for receiving a hook on a bed or wheel chair when the pump10 and bag 114 are to be removed from the docking station 100′ forfollowing a patient away from the fixed docking station array.

Each docking station 100′ is provided with three diodes 112′ forindicating status of the docking station and the pump as regards powersupply, pumping status and fluid supply or other parameters desiredmonitored. Each docking station furthermore has two opposed grooves forslidingly receiving the lateral edges of a frame 106′

The system of FIG. 25 affords great flexibiity as to number of infusionpumps per patient and as regards mode of transport together with thepatient either on the frame 106′ or removed therefrom.

1. (canceled)
 2. A portable infusion pump device for dispensing insulinto a user, comprising: a portable pump housing defining a space toreceive insulin; a user interface positioned on the portable pumphousing, the user interface comprising a display device for showing datarelated to insulin treatment; a piston rod defining an exterior threadpattern and linearly movable in an axial direction in the housing toadvance from a first position to a second position so as to dispenseinsulin from the pump housing when insulin is received in the pumphousing; a ratchet mechanism to urge the piston rod from the firstposition to the second position; a gear that is rotatable in anactivation direction to drive the piston rod from the first position tothe second position, wherein the ratchet mechanism comprises a ratchetbody that engages the gear, the ratchet body being adjustable from anon-activating position to an activating position so as to incrementallyrotate the gear in the activation direction, and wherein the ratchetbody maintains physical contact with the gear when moving between thenon-activating position and the activating position; and a spring devicethat provides a drive force to the ratchet mechanism to advance thepiston rod to the second position and thereby dispense insulin from thepump housing by mechanical power of the spring device when insulin isreceived in the pump housing.
 3. The portable infusion pump device ofclaim 2, wherein the ratchet mechanism further comprises a pawl devicethat engages the gear to prevent rotation of the gear in a directionopposite the activation direction.
 4. The portable infusion pump deviceof claim 2, wherein the spring device urges the ratchet body from thenon-activating position to the activating position so that the pistonrod is advanced to the second position by the mechanical power of thespring device.
 5. The portable infusion pump device of claim 2, furthercomprising an electrically powered actuator that provides a resetdisplacement force to the ratchet mechanism.
 6. The portable infusionpump device of claim 5, wherein the electrically powered actuatorincludes a shape memory device that provides a reset displacement forceto the ratchet mechanism.
 7. The portable infusion pump device of claim6, wherein the shape memory device shortens when heated by electricalcurrent so as to exert the reset displacement force upon the ratchetmechanism.
 8. The portable infusion pump device of claim 6, wherein thespring device is cocked when the shape memory device exerts the resetdisplacement force upon the ratchet mechanism.
 9. The portable infusionpump device of claim 2, wherein the spring device comprises at least onedevice selected from the group consisting of a tension spring, acompression spring, a flat spring, and a piston-and-cylinder mechanism.10. The portable infusion pump device of claim 2, wherein the userinterface further comprises one or more buttons for actuation.
 11. Theportable infusion pump device of claim 2, further comprising a batterypower source disposed in the pump housing.
 12. The portable infusionpump device of claim 2, wherein the pump housing defines the space toreceive a separate insulin container.
 13. The portable infusion pumpdevice of claim 2, wherein the piston rod is movable in the housing todispense the insulin from the pump housing according to a predeterminedsequence when the insulin is received in the pump housing.
 14. Theportable infusion pump device of claim 2, wherein the exterior threadpattern of the piston rod mates with an internal thread pattern of adriver gear so that rotation of the driver gear causes linearadvancement of the piston rod.
 15. The portable infusion pump device ofclaim 2, wherein the gear is a first gear that mates with a second gearhaving a different size, the second gear engaging with the piston rod toadvance from the piston rod from the first position to the secondposition when the first gear is rotated in the activation direction. 16.The portable infusion pump device of claim 2, wherein the gear isindirectly coupled to the piston rod via a gear reduction arrangement.